Commit Graph

79 Commits

Author SHA1 Message Date
Junio C Hamano
a1264a08a1 Merge branch 'en/header-split-cache-h-part-3'
Header files cleanup.

* en/header-split-cache-h-part-3: (28 commits)
  fsmonitor-ll.h: split this header out of fsmonitor.h
  hash-ll, hashmap: move oidhash() to hash-ll
  object-store-ll.h: split this header out of object-store.h
  khash: name the structs that khash declares
  merge-ll: rename from ll-merge
  git-compat-util.h: remove unneccessary include of wildmatch.h
  builtin.h: remove unneccessary includes
  list-objects-filter-options.h: remove unneccessary include
  diff.h: remove unnecessary include of oidset.h
  repository: remove unnecessary include of path.h
  log-tree: replace include of revision.h with simple forward declaration
  cache.h: remove this no-longer-used header
  read-cache*.h: move declarations for read-cache.c functions from cache.h
  repository.h: move declaration of the_index from cache.h
  merge.h: move declarations for merge.c from cache.h
  diff.h: move declaration for global in diff.c from cache.h
  preload-index.h: move declarations for preload-index.c from elsewhere
  sparse-index.h: move declarations for sparse-index.c from cache.h
  name-hash.h: move declarations for name-hash.c from cache.h
  run-command.h: move declarations for run-command.c from cache.h
  ...
2023-06-29 16:43:21 -07:00
Junio C Hamano
d9f9f6b358 Merge branch 'ds/disable-replace-refs'
Introduce a mechanism to disable replace refs globally and per
repository.

* ds/disable-replace-refs:
  repository: create read_replace_refs setting
  replace-objects: create wrapper around setting
  repository: create disable_replace_refs()
2023-06-22 16:29:06 -07:00
Junio C Hamano
f2ffc74186 Merge branch 'tb/pack-bitmap-traversal-with-boundary'
The object traversal using reachability bitmap done by
"pack-object" has been tweaked to take advantage of the fact that
using "boundary" commits as representative of all the uninteresting
ones can save quite a lot of object enumeration.

* tb/pack-bitmap-traversal-with-boundary:
  pack-bitmap.c: use commit boundary during bitmap traversal
  pack-bitmap.c: extract `fill_in_bitmap()`
  object: add object_array initializer helper function
2023-06-22 16:29:05 -07:00
Elijah Newren
c339932bd8 repository: remove unnecessary include of path.h
This also made it clear that several .c files that depended upon path.h
were missing a #include for it; add the missing includes while at it.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-06-21 13:39:53 -07:00
Elijah Newren
bc47f16db2 repository.h: move declaration of the_index from cache.h
the_index is a global variable defined in repository.c; as such, its
declaration feels better suited living in repository.h rather than
cache.h.  Move it.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-06-21 13:39:53 -07:00
Elijah Newren
fbffdfb11c preload-index.h: move declarations for preload-index.c from elsewhere
We already have a preload-index.c file; move the declarations for the
functions in that file into a new preload-index.h.  These were
previously split between cache.h and repository.h.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-06-21 13:39:53 -07:00
Derrick Stolee
9c7d1b057f repository: create read_replace_refs setting
The 'read_replace_refs' global specifies whether or not we should
respect the references of the form 'refs/replace/<oid>' to replace which
object we look up when asking for '<oid>'. This global has caused issues
when it is not initialized properly, such as in b6551feadf (merge-tree:
load default git config, 2023-05-10).

To make this more robust, move its config-based initialization out of
git_default_config and into prepare_repo_settings(). This provides a
repository-scoped version of the 'read_replace_refs' global.

The global still has its purpose: it is disabled process-wide by the
GIT_NO_REPLACE_OBJECTS environment variable or by a call to
disable_replace_refs() in some specific Git commands.

Since we already encapsulated the use of the constant inside
replace_refs_enabled(), we can perform the initialization inside that
method, if necessary. This solves the problem of forgetting to check the
config, as we will check it before returning this value.

Due to this encapsulation, the global can move to be static within
replace-object.c.

There is an interesting behavior change possible here: we now have a
repository-scoped understanding of this config value. Thus, if there was
a command that recurses into submodules and might follow replace refs,
then it would now respect the core.useReplaceRefs config value in each
repository.

'git grep --recurse-submodules' is such a command that recurses into
submodules in-process. We can demonstrate the granularity of this config
value via a test in t7814.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-06-12 13:34:55 -07:00
Victoria Dye
3867f6d650 repository: move 'repository_format_worktree_config' to repo scope
Move 'repository_format_worktree_config' out of the global scope and into
the 'repository' struct. This change is similar to how
'repository_format_partial_clone' was moved in ebaf3bcf1a (repository: move
global r_f_p_c to repo struct, 2021-06-17), adding it to the 'repository'
struct and updating 'setup.c' & 'repository.c' functions to assign the value
appropriately.

The primary goal of this change is to be able to load the worktree config of
a submodule depending on whether that submodule - not its superproject - has
'extensions.worktreeConfig' enabled. To ensure 'do_git_config_sequence()'
has access to the newly repo-scoped configuration, add a 'struct repository'
argument to 'do_git_config_sequence()' and pass it the 'repo' value from
'config_with_options()'.

Finally, add/update tests in 't3007-ls-files-recurse-submodules.sh' to
verify 'extensions.worktreeConfig' is read an used independently by
superprojects and submodules.

Signed-off-by: Victoria Dye <vdye@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-05-26 13:53:41 +09:00
Taylor Blau
b0afdce5da pack-bitmap.c: use commit boundary during bitmap traversal
When reachability bitmap coverage exists in a repository, Git will use a
different (and hopefully faster) traversal to compute revision walks.

Consider a set of positive and negative tips (which we'll refer to with
their standard bitmap parlance by "wants", and "haves"). In order to
figure out what objects exist between the tips, the existing traversal
in `prepare_bitmap_walk()` does something like:

  1. Consider if we can even compute the set of objects with bitmaps,
     and fall back to the usual traversal if we cannot. For example,
     pathspec limiting traversals can't be computed using bitmaps (since
     they don't know which objects are at which paths). The same is true
     of certain kinds of non-trivial object filters.

  2. If we can compute the traversal with bitmaps, partition the
     (dereferenced) tips into two object lists, "haves", and "wants",
     based on whether or not the objects have the UNINTERESTING flag,
     respectively.

  3. Fall back to the ordinary object traversal if either (a) there are
     more than zero haves, none of which are in the bitmapped pack or
     MIDX, or (b) there are no wants.

  4. Construct a reachability bitmap for the "haves" side by walking
     from the revision tips down to any existing bitmaps, OR-ing in any
     bitmaps as they are found.

  5. Then do the same for the "wants" side, stopping at any objects that
     appear in the "haves" bitmap.

  6. Filter the results if any object filter (that can be easily
     computed with bitmaps alone) was given, and then return back to the
     caller.

When there is good bitmap coverage relative to the traversal tips, this
walk is often significantly faster than an ordinary object traversal
because it can visit far fewer objects.

But in certain cases, it can be significantly *slower* than the usual
object traversal. Why? Because we need to compute complete bitmaps on
either side of the walk. If either one (or both) of the sides require
walking many (or all!) objects before they get to an existing bitmap,
the extra bitmap machinery is mostly or all overhead.

One of the benefits, however, is that even if the walk is slower, bitmap
traversals are guaranteed to provide an *exact* answer. Unlike the
traditional object traversal algorithm, which can over-count the results
by not opening trees for older commits, the bitmap walk builds an exact
reachability bitmap for either side, meaning the results are never
over-counted.

But producing non-exact results is OK for our traversal here (both in
the bitmap case and not), as long as the results are over-counted, not
under.

Relaxing the bitmap traversal to allow it to produce over-counted
results gives us the opportunity to make some significant improvements.
Instead of the above, the new algorithm only has to walk from the
*boundary* down to the nearest bitmap, instead of from each of the
UNINTERESTING tips.

The boundary-based approach still has degenerate cases, but we'll show
in a moment that it is often a significant improvement.

The new algorithm works as follows:

  1. Build a (partial) bitmap of the haves side by first OR-ing any
     bitmap(s) that already exist for UNINTERESTING commits between the
     haves and the boundary.

  2. For each commit along the boundary, add it as a fill-in traversal
     tip (where the traversal terminates once an existing bitmap is
     found), and perform fill-in traversal.

  3. Build up a complete bitmap of the wants side as usual, stopping any
     time we intersect the (partial) haves side.

  4. Return the results.

And is more-or-less equivalent to using the *old* algorithm with this
invocation:

    $ git rev-list --objects --use-bitmap-index $WANTS --not \
        $(git rev-list --objects --boundary $WANTS --not $HAVES |
          perl -lne 'print $1 if /^-(.*)/')

The new result performs significantly better in many cases, particularly
when the distance from the boundary commit(s) to an existing bitmap is
shorter than the distance from (all of) the have tips to the nearest
bitmapped commit.

Note that when using the old bitmap traversal algorithm, the results can
be *slower* than without bitmaps! Under the new algorithm, the result is
computed faster with bitmaps than without (at the cost of over-counting
the true number of objects in a similar fashion as the non-bitmap
traversal):

    # (Computing the number of tagged objects not on any branches
    # without bitmaps).
    $ time git rev-list --count --objects --tags --not --branches
    20

    real	0m1.388s
    user	0m1.092s
    sys	0m0.296s

    # (Computing the same query using the old bitmap traversal).
    $ time git rev-list --count --objects --tags --not --branches --use-bitmap-index
    19

    real	0m22.709s
    user	0m21.628s
    sys	0m1.076s

    # (this commit)
    $ time git.compile rev-list --count --objects --tags --not --branches --use-bitmap-index
    19

    real	0m1.518s
    user	0m1.234s
    sys	0m0.284s

The new algorithm is still slower than not using bitmaps at all, but it
is nearly a 15-fold improvement over the existing traversal.

In a more realistic setting (using my local copy of git.git), I can
observe a similar (if more modest) speed-up:

    $ argv="--count --objects --branches --not --tags"
    hyperfine \
      -n 'no bitmaps' "git.compile rev-list $argv" \
      -n 'existing traversal' "git.compile rev-list --use-bitmap-index $argv" \
      -n 'boundary traversal' "git.compile -c pack.useBitmapBoundaryTraversal=true rev-list --use-bitmap-index $argv"
    Benchmark 1: no bitmaps
      Time (mean ± σ):     124.6 ms ±   2.1 ms    [User: 103.7 ms, System: 20.8 ms]
      Range (min … max):   122.6 ms … 133.1 ms    22 runs

    Benchmark 2: existing traversal
      Time (mean ± σ):     368.6 ms ±   3.0 ms    [User: 325.3 ms, System: 43.1 ms]
      Range (min … max):   365.1 ms … 374.8 ms    10 runs

    Benchmark 3: boundary traversal
      Time (mean ± σ):     167.6 ms ±   0.9 ms    [User: 139.5 ms, System: 27.9 ms]
      Range (min … max):   166.1 ms … 169.2 ms    17 runs

    Summary
      'no bitmaps' ran
        1.34 ± 0.02 times faster than 'boundary traversal'
        2.96 ± 0.05 times faster than 'existing traversal'

Here, the new algorithm is also still slower than not using bitmaps, but
represents a more than 2-fold improvement over the existing traversal in
a more modest example.

Since this algorithm was originally written (nearly a year and a half
ago, at the time of writing), the bitmap lookup table shipped, making
the new algorithm's result more competitive. A few other future
directions for improving bitmap traversal times beyond not using bitmaps
at all:

  - Decrease the cost to decompress and OR together many bitmaps
    together (particularly when enumerating the uninteresting side of
    the walk). Here we could explore more efficient bitmap storage
    techniques, like Roaring+Run and/or use SIMD instructions to speed
    up ORing them together.

  - Store pseudo-merge bitmaps, which could allow us to OR together
    fewer "summary" bitmaps (which would also help with the above).

Helped-by: Jeff King <peff@peff.net>
Helped-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-05-08 12:05:55 -07:00
Junio C Hamano
fc23c397c7 Merge branch 'tb/enable-cruft-packs-by-default'
When "gc" needs to retain unreachable objects, packing them into
cruft packs (instead of exploding them into loose object files) has
been offered as a more efficient option for some time.  Now the use
of cruft packs has been made the default and no longer considered
an experimental feature.

* tb/enable-cruft-packs-by-default:
  repository.h: drop unused `gc_cruft_packs`
  builtin/gc.c: make `gc.cruftPacks` enabled by default
  t/t9300-fast-import.sh: prepare for `gc --cruft` by default
  t/t6500-gc.sh: add additional test cases
  t/t6500-gc.sh: refactor cruft pack tests
  t/t6501-freshen-objects.sh: prepare for `gc --cruft` by default
  t/t5304-prune.sh: prepare for `gc --cruft` by default
  builtin/gc.c: ignore cruft packs with `--keep-largest-pack`
  builtin/repack.c: fix incorrect reference to '-C'
  pack-write.c: plug a leak in stage_tmp_packfiles()
2023-04-28 16:03:03 -07:00
Taylor Blau
029a632c35 repository.h: drop unused gc_cruft_packs
As of the previous commit, all callers that need to read the value of
`gc.cruftPacks` do so outside without using the `repo_settings` struct,
making its `gc_cruft_packs` unused. Drop it accordingly.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-18 14:56:48 -07:00
Taylor Blau
dbcf611617 pack-revindex: introduce pack.readReverseIndex
Since 1615c567b8 (Documentation/config/pack.txt: advertise
'pack.writeReverseIndex', 2021-01-25), we have had the
`pack.writeReverseIndex` configuration option, which tells Git whether
or not it is allowed to write a ".rev" file when indexing a pack.

Introduce a complementary configuration knob, `pack.readReverseIndex` to
control whether or not Git will read any ".rev" file(s) that may be
available on disk.

This option is useful for debugging, as well as disabling the effect of
".rev" files in certain instances.

This is useful because of the trade-off[^1] between the time it takes to
generate a reverse index (slow from scratch, fast when reading an
existing ".rev" file), and the time it takes to access a record (the
opposite).

For example, even though it is faster to use the on-disk reverse index
when computing the on-disk size of a packed object, it is slower to
enumerate the same value for all objects.

Here are a couple of examples from linux.git. When computing the above
for a single object, using the on-disk reverse index is significantly
faster:

    $ git rev-parse HEAD >in
    $ hyperfine -L v false,true 'git.compile -c pack.readReverseIndex={v} cat-file --batch-check="%(objectsize:disk)" <in'
    Benchmark 1: git.compile -c pack.readReverseIndex=false cat-file --batch-check="%(objectsize:disk)" <in
      Time (mean ± σ):     302.5 ms ±  12.5 ms    [User: 258.7 ms, System: 43.6 ms]
      Range (min … max):   291.1 ms … 328.1 ms    10 runs

    Benchmark 2: git.compile -c pack.readReverseIndex=true cat-file --batch-check="%(objectsize:disk)" <in
      Time (mean ± σ):       3.9 ms ±   0.3 ms    [User: 1.6 ms, System: 2.4 ms]
      Range (min … max):     2.0 ms …   4.4 ms    801 runs

    Summary
      'git.compile -c pack.readReverseIndex=true cat-file --batch-check="%(objectsize:disk)" <in' ran
       77.29 ± 7.14 times faster than 'git.compile -c pack.readReverseIndex=false cat-file --batch-check="%(objectsize:disk)" <in'

, but when instead trying to compute the on-disk object size for all
objects in the repository, using the ".rev" file is a disadvantage over
creating the reverse index from scratch:

    $ hyperfine -L v false,true 'git.compile -c pack.readReverseIndex={v} cat-file --batch-check="%(objectsize:disk)" --batch-all-objects'
    Benchmark 1: git.compile -c pack.readReverseIndex=false cat-file --batch-check="%(objectsize:disk)" --batch-all-objects
      Time (mean ± σ):      8.258 s ±  0.035 s    [User: 7.949 s, System: 0.308 s]
      Range (min … max):    8.199 s …  8.293 s    10 runs

    Benchmark 2: git.compile -c pack.readReverseIndex=true cat-file --batch-check="%(objectsize:disk)" --batch-all-objects
      Time (mean ± σ):     16.976 s ±  0.107 s    [User: 16.706 s, System: 0.268 s]
      Range (min … max):   16.839 s … 17.105 s    10 runs

    Summary
      'git.compile -c pack.readReverseIndex=false cat-file --batch-check="%(objectsize:disk)" --batch-all-objects' ran
	2.06 ± 0.02 times faster than 'git.compile -c pack.readReverseIndex=true cat-file --batch-check="%(objectsize:disk)" --batch-all-objects'

Luckily, the results when running `git cat-file` with `--unordered` are
closer together:

    $ hyperfine -L v false,true 'git.compile -c pack.readReverseIndex={v} cat-file --unordered --batch-check="%(objectsize:disk)" --batch-all-objects'
    Benchmark 1: git.compile -c pack.readReverseIndex=false cat-file --unordered --batch-check="%(objectsize:disk)" --batch-all-objects
      Time (mean ± σ):      5.066 s ±  0.105 s    [User: 4.792 s, System: 0.274 s]
      Range (min … max):    4.943 s …  5.220 s    10 runs

    Benchmark 2: git.compile -c pack.readReverseIndex=true cat-file --unordered --batch-check="%(objectsize:disk)" --batch-all-objects
      Time (mean ± σ):      6.193 s ±  0.069 s    [User: 5.937 s, System: 0.255 s]
      Range (min … max):    6.145 s …  6.356 s    10 runs

    Summary
      'git.compile -c pack.readReverseIndex=false cat-file --unordered --batch-check="%(objectsize:disk)" --batch-all-objects' ran
        1.22 ± 0.03 times faster than 'git.compile -c pack.readReverseIndex=true cat-file --unordered --batch-check="%(objectsize:disk)" --batch-all-objects'

Because the equilibrium point between these two is highly machine- and
repository-dependent, allow users to configure whether or not they will
read any ".rev" file(s) with this configuration knob.

[^1]: Generating a reverse index in memory takes O(N) time (where N is
  the number of objects in the repository), since we use a radix sort.
  Reading an entry from an on-disk ".rev" file is slower since each
  operation is bound by disk I/O instead of memory I/O.

  In order to compute the on-disk size of a packed object, we need to
  find the offset of our object, and the adjacent object (the on-disk
  size difference of these two). Finding the first offset requires a
  binary search. Finding the latter involves a single .rev lookup.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Acked-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-13 07:55:46 -07:00
Elijah Newren
f332121e75 treewide: remove unnecessary git-compat-util.h includes in headers
For sanity, we should probably do one of the following:

(a) make C and header files both depend upon everything they need
(b) consistently exclude git-compat-util.h from headers and require it
    be the first include in C files

Currently, we have some of the headers following (a) and others
following (b), which makes things messy.  In the past I was pushed
towards (b), as per [1] and [2].  Further, during this series I
discovered that this mixture empirically will mean that we end up with C
files that do not directly include git-compat-util.h, and do include
headers that don't include git-compat-util.h, with the result that we
likely have headers included before an indirect inclusion of
git-compat-util.h.  Since git-compat-util.h has tricky platform-specific
stuff that is meant to be included before everything else, this state of
affairs is risky and may lead to things breaking in subtle ways (and
only on some platforms) as per [1] and [2].

Since including git-compat-util.h in existing header files makes it
harder for us to catch C files that are missing that include, let's
switch to (b) to make the enforcement of this rule easier.  Remove the
inclusion of git-compat-util.h from header files other than the ones
that have been approved as alternate first includes.

[1] https://lore.kernel.org/git/20180811173406.GA9119@sigill.intra.peff.net/
[2] https://lore.kernel.org/git/20180811174301.GA9287@sigill.intra.peff.net/

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-02-23 17:25:28 -08:00
Derrick Stolee
17194b195d features: feature.manyFiles implies fast index writes
The recent addition of the index.skipHash config option allows index
writes to speed up by skipping the hash computation for the trailing
checksum. This is particularly critical for repositories with many files
at HEAD, so add this config option to two cases where users in that
scenario may opt-in to such behavior:

 1. The feature.manyFiles config option enables some options that are
    helpful for repositories with many files at HEAD.

 2. 'scalar register' and 'scalar reconfigure' set config options that
    optimize for large repositories.

In both of these cases, set index.skipHash=true to gain this
speedup. Add tests that demonstrate the proper way that
index.skipHash=true can override feature.manyFiles=true.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-01-07 07:46:14 +09:00
Taylor Blau
bdd42e34e3 Merge branch 'es/mark-gc-cruft-as-experimental'
Enable gc.cruftpacks by default for those who opt into
feature.experimental setting.

* es/mark-gc-cruft-as-experimental:
  config: let feature.experimental imply gc.cruftPacks=true
  gc: add tests for --cruft and friends
2022-11-08 17:14:48 -05:00
Emily Shaffer
c695592850 config: let feature.experimental imply gc.cruftPacks=true
We are interested in exploring whether gc.cruftPacks=true should become
the default value.

To determine whether it is safe to do so, let's encourage more users to
try it out.

Users who have set feature.experimental=true have already volunteered to
try new and possibly-breaking config changes, so let's try this new
default with that set of users.

Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-10-26 14:39:31 -07:00
Junio C Hamano
f322e9f51b Merge branch 'ab/submodule-helper-prep'
Code clean-up of "git submodule--helper".

* ab/submodule-helper-prep: (33 commits)
  submodule--helper: fix bad config API usage
  submodule--helper: libify even more "die" paths for module_update()
  submodule--helper: libify more "die" paths for module_update()
  submodule--helper: check repo{_submodule,}_init() return values
  submodule--helper: libify "must_die_on_failure" code paths (for die)
  submodule--helper update: don't override 'checkout' exit code
  submodule--helper: libify "must_die_on_failure" code paths
  submodule--helper: libify determine_submodule_update_strategy()
  submodule--helper: don't exit() on failure, return
  submodule--helper: use "code" in run_update_command()
  submodule API: don't handle SM_..{UNSPECIFIED,COMMAND} in to_string()
  submodule--helper: don't call submodule_strategy_to_string() in BUG()
  submodule--helper: add missing braces to "else" arm
  submodule--helper: return "ret", not "1" from update_submodule()
  submodule--helper: rename "int res" to "int ret"
  submodule--helper: don't redundantly check "else if (res)"
  submodule--helper: refactor "errmsg_str" to be a "struct strbuf"
  submodule--helper: add "const" to passed "struct update_data"
  submodule--helper: add "const" to copy of "update_data"
  submodule--helper: add "const" to passed "module_clone_data"
  ...
2022-09-13 11:38:23 -07:00
Ævar Arnfjörð Bjarmason
1e8697b5c4 submodule--helper: check repo{_submodule,}_init() return values
Fix code added in ce125d431a (submodule: extract path to submodule
gitdir func, 2021-09-15) and a77c3fcb5e (submodule--helper: get
remote names from any repository, 2022-03-04) which failed to check
the return values of repo_init() and repo_submodule_init(). If we
failed to initialize the repository or submodule we could segfault
when trying to access the invalid repository structs.

Let's also check that these were the only such logic errors in the
codebase by making use of the "warn_unused_result" attribute. This is
valid as of GCC 3.4.0 (and clang will catch it via its faking of
__GNUC__ ).

As the comment being added to git-compat-util.h we're piggy-backing on
the LAST_ARG_MUST_BE_NULL version check out of lazyness. See
9fe3edc47f (Add the LAST_ARG_MUST_BE_NULL macro, 2013-07-18) for its
addition. The marginal benefit of covering gcc 3.4.0..4.0.0 is
near-zero (or zero) at this point. It mostly matters that we catch
this somewhere.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Reviewed-by: Glen Choo <chooglen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-09-02 09:16:24 -07:00
Taylor Blau
a92d8523ce commit-graph: pass repo_settings instead of repository
The parse_commit_graph() function takes a 'struct repository *' pointer,
but it only ever accesses config settings (either directly or through
the .settings field of the repo struct). Move all relevant config
settings into the repo_settings struct, and update parse_commit_graph()
and its existing callers so that it takes 'struct repo_settings *'
instead.

Callers of parse_commit_graph() will now need to call
prepare_repo_settings() themselves, or initialize a 'struct
repo_settings' directly.

Prior to ab14d0676c (commit-graph: pass a 'struct repository *' in more
places, 2020-09-09), parsing a commit-graph was a pure function
depending only on the contents of the commit-graph itself. Commit
ab14d0676c introduced a dependency on a `struct repository` pointer, and
later commits such as b66d84756f (commit-graph: respect
'commitGraph.readChangedPaths', 2020-09-09) added dependencies on config
settings, which were accessed through the `settings` field of the
repository pointer. This field was initialized via a call to
`prepare_repo_settings()`.

Additionally, this fixes an issue in fuzz-commit-graph: In 44c7e62
(2021-12-06, repo-settings:prepare_repo_settings only in git repos),
prepare_repo_settings was changed to issue a BUG() if it is called by a
process whose CWD is not a Git repository.

The combination of commits mentioned above broke fuzz-commit-graph,
which attempts to parse arbitrary fuzzing-engine-provided bytes as a
commit graph file. Prior to this change, parse_commit_graph() called
prepare_repo_settings(), but since we run the fuzz tests without a valid
repository, we are hitting the BUG() from 44c7e62 for every test case.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-07-14 15:42:17 -07:00
Junio C Hamano
439c1e6d5d Merge branch 'jh/builtin-fsmonitor-part2'
Built-in fsmonitor (part 2).

* jh/builtin-fsmonitor-part2: (30 commits)
  t7527: test status with untracked-cache and fsmonitor--daemon
  fsmonitor: force update index after large responses
  fsmonitor--daemon: use a cookie file to sync with file system
  fsmonitor--daemon: periodically truncate list of modified files
  t/perf/p7519: add fsmonitor--daemon test cases
  t/perf/p7519: speed up test on Windows
  t/perf/p7519: fix coding style
  t/helper/test-chmtime: skip directories on Windows
  t/perf: avoid copying builtin fsmonitor files into test repo
  t7527: create test for fsmonitor--daemon
  t/helper/fsmonitor-client: create IPC client to talk to FSMonitor Daemon
  help: include fsmonitor--daemon feature flag in version info
  fsmonitor--daemon: implement handle_client callback
  compat/fsmonitor/fsm-listen-darwin: implement FSEvent listener on MacOS
  compat/fsmonitor/fsm-listen-darwin: add MacOS header files for FSEvent
  compat/fsmonitor/fsm-listen-win32: implement FSMonitor backend on Windows
  fsmonitor--daemon: create token-based changed path cache
  fsmonitor--daemon: define token-ids
  fsmonitor--daemon: add pathname classification
  fsmonitor--daemon: implement 'start' command
  ...
2022-04-04 10:56:24 -07:00
Jeff Hostetler
1e0ea5c431 fsmonitor: config settings are repository-specific
Move fsmonitor config settings to a new and opaque
`struct fsmonitor_settings` structure.  Add a lazily-loaded pointer
to this into `struct repo_settings`

Create an `enum fsmonitor_mode` type in `struct fsmonitor_settings` to
represent the state of fsmonitor.  This lets us represent which, if
any, fsmonitor provider (hook or IPC) is enabled.

Create `fsm_settings__get_*()` getters to lazily look up fsmonitor-
related config settings.

Get rid of the `core_fsmonitor` global variable.  Move the code to
lookup the existing `core.fsmonitor` config value into the fsmonitor
settings.

Create a hook pathname variable in `struct fsmonitor-settings` and
only set it when in hook mode.

Extend the definition of `core.fsmonitor` to be either a boolean
or a hook pathname.  When true, the builtin FSMonitor is used.
When false or unset, no FSMonitor (neither builtin nor hook) is
used.

The existing `core_fsmonitor` global variable was used to store the
pathname to the fsmonitor hook *and* it was used as a boolean to see
if fsmonitor was enabled.  This dual usage and global visibility leads
to confusion when we add the IPC-based provider.  So lets hide the
details in fsmonitor-settings.c and let it decide which provider to
use in the case of multiple settings.  This avoids cluttering up
repo-settings.c with these private details.

A future commit in builtin-fsmonitor series will add the ability to
disqualify worktrees for various reasons, such as being mounted from a
remote volume, where fsmonitor should not be started.  Having the
config settings hidden in fsmonitor-settings.c allows such worktree
restrictions to override the config values used.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-03-25 16:04:15 -07:00
Ævar Arnfjörð Bjarmason
759f340738 repository.c: free the "path cache" in repo_clear()
The "struct path_cache" added in 102de880d2 (path.c: migrate global
git_path_* to take a repository argument, 2018-05-17) is only used
directly by code in repository.[ch] (but populated in path.[ch]).

Let's move this code to repository.[ch], and stop leaking this memory
when we run repo_clear(). To avoid the cast change it from a "const
char *" to a "char *".

This also removes the "PATH_CACHE_INIT" macro, which has never been
used for anything. For the "struct repository" we already make a hard
assumption that it (and "the_repository") can be identically
initialized by making it a "static" variable, so making use of a
"PATH_CACHE_INIT" somewhere would have been confusing.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-03-04 13:24:19 -08:00
Junio C Hamano
70ff41ffcf Merge branch 'en/fetch-negotiation-default-fix'
Interaction between fetch.negotiationAlgorithm and
feature.experimental configuration variables has been corrected.

* en/fetch-negotiation-default-fix:
  repo-settings: rename the traditional default fetch.negotiationAlgorithm
  repo-settings: fix error handling for unknown values
  repo-settings: fix checking for fetch.negotiationAlgorithm=default
2022-02-16 15:14:30 -08:00
Elijah Newren
714edc620c repo-settings: rename the traditional default fetch.negotiationAlgorithm
Give the traditional default fetch.negotiationAlgorithm the name
'consecutive'.  Also allow a choice of 'default' to have Git decide
between the choices (currently, picking 'skipping' if
feature.experimental is true and 'consecutive' otherwise).  Update the
documentation accordingly.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-02-02 09:36:17 -08:00
Junio C Hamano
0dc90d954d Merge branch 'ns/tmp-objdir'
New interface into the tmp-objdir API to help in-core use of the
quarantine feature.

* ns/tmp-objdir:
  tmp-objdir: disable ref updates when replacing the primary odb
  tmp-objdir: new API for creating temporary writable databases
2022-01-03 16:24:15 -08:00
Neeraj Singh
ecd81dfc79 tmp-objdir: disable ref updates when replacing the primary odb
When creating a subprocess with a temporary ODB, we set the
GIT_QUARANTINE_ENVIRONMENT env var to tell child Git processes not
to update refs, since the tmp-objdir may go away.

Introduce a similar mechanism for in-process temporary ODBs when
we call tmp_objdir_replace_primary_odb. Now both mechanisms set
the disable_ref_updates flag on the odb, which is queried by
the ref_transaction_prepare function.

Peff's test case [1] was invoking ref updates via the cachetextconv
setting. That particular code silently does nothing when a ref
update is forbidden. See the call to notes_cache_put in
fill_textconv where errors are ignored.

[1] https://lore.kernel.org/git/YVOn3hDsb5pnxR53@coredump.intra.peff.net/

Reported-by: Jeff King <peff@peff.net>
Signed-off-by: Neeraj Singh <neerajsi@microsoft.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-08 14:06:46 -08:00
Glen Choo
fd3cb0501e remote: move static variables into per-repository struct
remote.c does not works with non-the_repository because it stores its
state as static variables. To support non-the_repository, we can use a
per-repository struct for the remotes subsystem.

Prepare for this change by defining a struct remote_state that holds
the remotes subsystem state and move the static variables of remote.c
into the_repository->remote_state.

This introduces no behavioral or API changes.

Signed-off-by: Glen Choo <chooglen@google.com>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-11-18 22:31:19 -08:00
Junio C Hamano
d8d33378ed Merge branch 'ab/repo-settings-cleanup'
Code cleanup.

* ab/repo-settings-cleanup:
  repository.h: don't use a mix of int and bitfields
  repo-settings.c: simplify the setup
  read-cache & fetch-negotiator: check "enum" values in switch()
  environment.c: remove test-specific "ignore_untracked..." variable
  wrapper.c: add x{un,}setenv(), and use xsetenv() in environment.c
2021-10-06 13:40:11 -07:00
Ævar Arnfjörð Bjarmason
c21919f1b2 repository.h: don't use a mix of int and bitfields
Change the bitfield added in 58300f4743 (sparse-index: add
index.sparse config option, 2021-03-30) and 3964fc2aae (sparse-index:
add guard to ensure full index, 2021-03-30) to just use an "int"
boolean instead.

It might be smart to optimize the space here in the future, but by
consistently using an "int" we can take its address and pass it to
repo_cfg_bool(), and therefore don't need to handle "sparse_index" as
a special-case when reading the "index.sparse" setting.

There's no corresponding config for "command_requires_full_index", but
let's change it too for consistency and to prevent future bugs
creeping in due to one of these being "unsigned".

Using "int" consistently also prevents subtle bugs or undesired
control flow creeping in here. Before the preceding commit the
initialization of "command_requires_full_index" in
prepare_repo_settings() did nothing, i.e. this:

    r->settings.command_requires_full_index = 1

Was redundant to the earlier memset() to -1. Likewise for
"sparse_index" added in 58300f4743 (sparse-index: add index.sparse
config option, 2021-03-30) the code and comment added there was
misleading, we weren't initializing it to off, but re-initializing it
from "1" to "0", and then finally checking the config, and perhaps
setting it to "1" again. I.e. we could have applied this patch before
the preceding commit:

	+	assert(r->settings.command_requires_full_index == 1);
	 	r->settings.command_requires_full_index = 1;

	 	/*
	 	 * Initialize this as off.
	 	 */
	+	assert(r->settings.sparse_index == 1);
	 	r->settings.sparse_index = 0;
	 	if (!repo_config_get_bool(r, "index.sparse", &value) && value)
	 		r->settings.sparse_index = 1;

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-22 13:15:00 -07:00
Ævar Arnfjörð Bjarmason
3050b6dfc7 repo-settings.c: simplify the setup
Simplify the setup code in repo-settings.c in various ways, making the
code shorter, easier to read, and requiring fewer hacks to do the same
thing as it did before:

Since 7211b9e753 (repo-settings: consolidate some config settings,
2019-08-13) we have memset() the whole "settings" structure to -1 in
prepare_repo_settings(), and subsequently relied on the -1 value.

Most of the fields did not need to be initialized to -1, and because
we were doing that we had the enum labels "UNTRACKED_CACHE_UNSET" and
"FETCH_NEGOTIATION_UNSET" purely to reflect the resulting state
created this memset() in prepare_repo_settings(). No other code used
or relied on them, more on that below.

For the rest most of the subsequent "are we -1, then read xyz" can
simply be removed by re-arranging what we read first. E.g. when
setting the "index.version" setting we should have first read
"feature.experimental", so that it (and "feature.manyfiles") can
provide a default for our "index.version".

Instead the code setting it, added when "feature.manyFiles"[1] was
created, was using the UPDATE_DEFAULT_BOOL() macro added in an earlier
commit[2]. That macro is now gone, since it was only needed for this
pattern of reading things in the wrong order.

This also fixes an (admittedly obscure) logic error where we'd
conflate an explicit "-1" value in the config with our own earlier
memset() -1.

We can also remove the UPDATE_DEFAULT_BOOL() wrapper added in
[3]. Using it is redundant to simply using the return value from
repo_config_get_bool(), which is non-zero if the provided key exists
in the config.

Details on edge cases relating to the memset() to -1, continued from
"more on that below" above:

 * UNTRACKED_CACHE_KEEP:

   In [4] the "unset" and "keep" handling for core.untrackedCache was
   consolidated. But it while we understand the "keep" value, we don't
   handle it differently than the case of any other unknown value.

   So let's retain UNTRACKED_CACHE_KEEP and remove the
   UNTRACKED_CACHE_UNSET setting (which was always implicitly
   UNTRACKED_CACHE_KEEP before). We don't need to inform any code
   after prepare_repo_settings() that the setting was "unset", as far
   as anyone else is concerned it's core.untrackedCache=keep. if
   "core.untrackedcache" isn't present in the config.

 * FETCH_NEGOTIATION_UNSET & FETCH_NEGOTIATION_NONE:

   Since these two two enum fields added in [5] don't rely on the
   memzero() setting them to "-1" anymore we don't have to provide
   them with explicit values.

1. c6cc4c5afd (repo-settings: create feature.manyFiles setting,
   2019-08-13)
2. 31b1de6a09 (commit-graph: turn on commit-graph by default,
   2019-08-13)
3. 31b1de6a09 (commit-graph: turn on commit-graph by default,
   2019-08-13)
4. ad0fb65999 (repo-settings: parse core.untrackedCache,
   2019-08-13)
5. aaf633c2ad (repo-settings: create feature.experimental setting,
   2019-08-13)

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-22 13:15:00 -07:00
Jonathan Tan
8eb8dcf946 repository: support unabsorbed in repo_submodule_init
In preparation for a subsequent commit that migrates code using
add_submodule_odb() to repo_submodule_init(), teach
repo_submodule_init() to support submodules with unabsorbed gitdirs.
(See the documentation for "git submodule absorbgitdirs" for more
information about absorbed and unabsorbed gitdirs.)

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-09 14:09:30 -07:00
Jonathan Tan
ef7dc2e9cc promisor-remote: support per-repository config
Instead of using global variables to store promisor remote information,
store this config in struct repository instead, and add
repository-agnostic non-static functions corresponding to the existing
non-static functions that only work on the_repository.

The actual lazy-fetching of missing objects currently does not work on
repositories other than the_repository, and will still not work after
this commit, so add a BUG message explaining this. A subsequent commit
will remove this limitation.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-06-28 09:57:42 -07:00
Jonathan Tan
ebaf3bcf1a repository: move global r_f_p_c to repo struct
Move repository_format_partial_clone, which is currently a global
variable, into struct repository. (Full support for per-repository
partial clone config will be done in a subsequent commit - this is split
into its own commit because of the extent of the changes needed.)

The new repo-specific variable cannot be set in
check_repository_format_gently() (as is currently), because that
function does not know which repo it is operating on (or even whether
the value is important); therefore this responsibility is delegated to
the outermost caller that knows. Of all the outermost callers that know
(found by looking at all functions that call clear_repository_format()),
I looked at those that either read from the main Git directory or write
into a struct repository. These callers have been modified accordingly
(write to the_repository in the former case and write to the given
struct repository in the latter case).

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-06-28 09:57:41 -07:00
Derrick Stolee
58300f4743 sparse-index: add index.sparse config option
When enabled, this config option signals that index writes should
attempt to use sparse-directory entries.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-30 12:57:47 -07:00
Derrick Stolee
3964fc2aae sparse-index: add guard to ensure full index
Upcoming changes will introduce modifications to the index format that
allow sparse directories. It will be useful to have a mechanism for
converting those sparse index files into full indexes by walking the
tree at those sparse directories. Name this method ensure_full_index()
as it will guarantee that the index is fully expanded.

This method is not implemented yet, and instead we focus on the
scaffolding to declare it and call it at the appropriate time.

Add a 'command_requires_full_index' member to struct repo_settings. This
will be an indicator that we need the index in full mode to do certain
index operations. This starts as being true for every command, then we
will set it to false as some commands integrate with sparse indexes.

If 'command_requires_full_index' is true, then we will immediately
expand a sparse index to a full one upon reading from disk. This
suffices for now, but we will want to add more callers to
ensure_full_index() later.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-30 12:57:45 -07:00
Junio C Hamano
52b8c8c716 Merge branch 'ds/maintenance-part-2'
"git maintenance", an extended big brother of "git gc", continues
to evolve.

* ds/maintenance-part-2:
  maintenance: add incremental-repack auto condition
  maintenance: auto-size incremental-repack batch
  maintenance: add incremental-repack task
  midx: use start_delayed_progress()
  midx: enable core.multiPackIndex by default
  maintenance: create auto condition for loose-objects
  maintenance: add loose-objects task
  maintenance: add prefetch task
2020-10-27 15:09:47 -07:00
Junio C Hamano
288ed98bf7 Merge branch 'tb/bloom-improvements'
"git commit-graph write" learned to limit the number of bloom
filters that are computed from scratch with the --max-new-filters
option.

* tb/bloom-improvements:
  commit-graph: introduce 'commitGraph.maxNewFilters'
  builtin/commit-graph.c: introduce '--max-new-filters=<n>'
  commit-graph: rename 'split_commit_graph_opts'
  bloom: encode out-of-bounds filters as non-empty
  bloom/diff: properly short-circuit on max_changes
  bloom: use provided 'struct bloom_filter_settings'
  bloom: split 'get_bloom_filter()' in two
  commit-graph.c: store maximum changed paths
  commit-graph: respect 'commitGraph.readChangedPaths'
  t/helper/test-read-graph.c: prepare repo settings
  commit-graph: pass a 'struct repository *' in more places
  t4216: use an '&&'-chain
  commit-graph: introduce 'get_bloom_filter_settings()'
2020-09-29 14:01:20 -07:00
Derrick Stolee
18e449f86b midx: enable core.multiPackIndex by default
The core.multiPackIndex setting has been around since c4d25228eb
(config: create core.multiPackIndex setting, 2018-07-12), but has been
disabled by default. If a user wishes to use the multi-pack-index
feature, then they must enable this config and run 'git multi-pack-index
write'.

The multi-pack-index feature is relatively stable now, so make the
config option true by default. For users that do not use a
multi-pack-index, the only extra cost will be a file lookup to see if a
multi-pack-index file exists (once per process, per object directory).

Also, this config option will be referenced by an upcoming
"incremental-repack" task in the maintenance builtin, so move the config
option into the repository settings struct. Note that if
GIT_TEST_MULTI_PACK_INDEX=1, then we want to ignore the config option
and treat core.multiPackIndex as enabled.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-25 10:53:04 -07:00
Taylor Blau
b66d84756f commit-graph: respect 'commitGraph.readChangedPaths'
Git uses the 'core.commitGraph' configuration value to control whether
or not the commit graph is used when parsing commits or performing a
traversal.

Now that commit-graphs can also contain a section for changed-path Bloom
filters, administrators that already have commit-graphs may find it
convenient to use those graphs without relying on their changed-path
Bloom filters. This can happen, for example, during a staged roll-out,
or in the event of an incident.

Introduce 'commitGraph.readChangedPaths' to control whether or not Bloom
filters are read. Note that this configuration is independent from both:

  - 'core.commitGraph', to allow flexibility in using all parts of a
    commit-graph _except_ for its Bloom filters.

  - The '--changed-paths' option for 'git commit-graph write', to allow
    reading and writing Bloom filters to be controlled independently.

When the variable is set, pretend as if no Bloom data was specified at
all. This avoids adding additional special-casing outside of the
commit-graph internals.

Suggested-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-09-09 12:51:48 -07:00
Jonathan Tan
cbe566a071 negotiator/noop: add noop fetch negotiator
Add a noop fetch negotiator. This is introduced to allow partial clones
to skip the unneeded negotiation step when fetching missing objects
using a "git fetch" subprocess. (The implementation of spawning a "git
fetch" subprocess will be done in a subsequent patch.) But this can also
be useful for end users, e.g. as a blunt fix for object corruption.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-08-18 13:25:05 -07:00
Xin Li
16af5f1abb repository: add a helper function to perform repository format upgrade
In version 1 of repository format, "extensions" gained special meaning
and it is safer to avoid upgrading when there are pre-existing
extensions.

Make list-objects-filter to use the helper function instead of setting
repository version directly as a prerequisite of exposing the upgrade
capability.

Signed-off-by: Xin Li <delphij@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-05 10:13:30 -07:00
Junio C Hamano
95ca48973d Merge branch 'jc/missing-ref-store-fix'
We've left the command line parsing of "git log :/a/b/" broken for
about a full year without anybody noticing, which has been
corrected.

* jc/missing-ref-store-fix:
  repository: mark the "refs" pointer as private
  sha1-name: do not assume that the ref store is initialized
2020-04-22 13:42:55 -07:00
Jeff King
0220461071 repository: mark the "refs" pointer as private
The "refs" pointer in a struct repository starts life as NULL, but then
is lazily initialized when it is accessed via get_main_ref_store().
However, it's easy for calling code to forget this and access it
directly, leading to code which works _some_ of the time, but fails if
it is called before anybody else accesses the refs.

This was the cause of the bug fixed by 5ff4b920eb (sha1-name: do not
assume that the ref store is initialized, 2020-04-09). In order to
prevent similar bugs, let's more clearly mark the "refs" field as
private.

In addition to helping future code, the name change will help us audit
any existing direct uses. Besides get_main_ref_store() itself, it turns
out there is only one. But we know it's OK as it is on the line directly
after the fix from 5ff4b920eb, which will have initialized the pointer.
However it's still a good idea for it to model the proper use of the
accessing function, so we'll convert it.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-09 22:40:48 -07:00
Elijah Newren
15beaaa3d1 Fix spelling errors in code comments
Reported-by: Jens Schleusener <Jens.Schleusener@fossies.org>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-11-10 16:00:54 +09:00
Junio C Hamano
098e8c6716 Merge branch 'jk/disable-commit-graph-during-upload-pack'
The "upload-pack" (the counterpart of "git fetch") needs to disable
commit-graph when responding to a shallow clone/fetch request, but
the way this was done made Git panic, which has been corrected.

* jk/disable-commit-graph-during-upload-pack:
  upload-pack: disable commit graph more gently for shallow traversal
  commit-graph: bump DIE_ON_LOAD check to actual load-time
2019-10-07 11:32:55 +09:00
Jeff King
6abada1880 upload-pack: disable commit graph more gently for shallow traversal
When the client has asked for certain shallow options like
"deepen-since", we do a custom rev-list walk that pretends to be
shallow. Before doing so, we have to disable the commit-graph, since it
is not compatible with the shallow view of the repository. That's
handled by 829a321569 (commit-graph: close_commit_graph before shallow
walk, 2018-08-20). That commit literally closes and frees our
repo->objects->commit_graph struct.

That creates an interesting problem for commits that have _already_ been
parsed using the commit graph. Their commit->object.parsed flag is set,
their commit->graph_pos is set, but their commit->maybe_tree may still
be NULL. When somebody later calls repo_get_commit_tree(), we see that
we haven't loaded the tree oid yet and try to get it from the commit
graph. But since it has been freed, we segfault!

So the root of the issue is a data dependency between the commit's
lazy-load of the tree oid and the fact that the commit graph can go
away mid-process. How can we resolve it?

There are a couple of general approaches:

  1. The obvious answer is to avoid loading the tree from the graph when
     we see that it's NULL. But then what do we return for the tree oid?
     If we return NULL, our caller in do_traverse() will rightly
     complain that we have no tree. We'd have to fallback to loading the
     actual commit object and re-parsing it. That requires teaching
     parse_commit_buffer() to understand re-parsing (i.e., not starting
     from a clean slate and not leaking any allocated bits like parent
     list pointers).

  2. When we close the commit graph, walk through the set of in-memory
     objects and clear any graph_pos pointers. But this means we also
     have to "unparse" any such commits so that we know they still need
     to open the commit object to fill in their trees. So it's no less
     complicated than (1), and is more expensive (since we clear objects
     we might not later need).

  3. Stop freeing the commit-graph struct. Continue to let it be used
     for lazy-loads of tree oids, but let upload-pack specify that it
     shouldn't be used for further commit parsing.

  4. Push the whole shallow rev-list out to its own sub-process, with
     the commit-graph disabled from the start, giving it a clean memory
     space to work from.

I've chosen (3) here. Options (1) and (2) would work, but are
non-trivial to implement. Option (4) is more expensive, and I'm not sure
how complicated it is (shelling out for the actual rev-list part is
easy, but we do then parse the resulting commits internally, and I'm not
clear which parts need to be handling shallow-ness).

The new test in t5500 triggers this segfault, but see the comments there
for how horribly intimate it has to be with how both upload-pack and
commit graphs work.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-09-12 12:30:08 -07:00
Derrick Stolee
50f26bd035 fetch: add fetch.writeCommitGraph config setting
The commit-graph feature is now on by default, and is being
written during 'git gc' by default. Typically, Git only writes
a commit-graph when a 'git gc --auto' command passes the gc.auto
setting to actualy do work. This means that a commit-graph will
typically fall behind the commits that are being used every day.

To stay updated with the latest commits, add a step to 'git
fetch' to write a commit-graph after fetching new objects. The
fetch.writeCommitGraph config setting enables writing a split
commit-graph, so on average the cost of writing this file is
very small. Occasionally, the commit-graph chain will collapse
to a single level, and this could be slow for very large repos.

For additional use, adjust the default to be true when
feature.experimental is enabled.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-09-03 12:06:14 -07:00
Derrick Stolee
aaf633c2ad repo-settings: create feature.experimental setting
The 'feature.experimental' setting includes config options that are
not committed to become defaults, but could use additional testing.

Update the following config settings to take new defaults, and to
use the repo_settings struct if not already using them:

* 'pack.useSparse=true'

* 'fetch.negotiationAlgorithm=skipping'

In the case of fetch.negotiationAlgorithm, the existing logic
would load the config option only when about to use the setting,
so had a die() statement on an unknown string value. This is
removed as now the config is parsed under prepare_repo_settings().
In general, this die() is probably misplaced and not valuable.
A test was removed that checked this die() statement executed.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-08-13 13:33:55 -07:00
Derrick Stolee
ad0fb65999 repo-settings: parse core.untrackedCache
The core.untrackedCache config setting is slightly complicated,
so clarify its use and centralize its parsing into the repo
settings.

The default value is "keep" (returned as -1), which persists the
untracked cache if it exists.

If the value is set as "false" (returned as 0), then remove the
untracked cache if it exists.

If the value is set as "true" (returned as 1), then write the
untracked cache and persist it.

Instead of relying on magic values of -1, 0, and 1, split these
options into an enum. This allows the use of "-1" as a
default value. After parsing the config options, if the value is
unset we can initialize it to UNTRACKED_CACHE_KEEP.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-08-13 13:33:55 -07:00
Derrick Stolee
7211b9e753 repo-settings: consolidate some config settings
There are a few important config settings that are not loaded
during git_default_config. These are instead loaded on-demand.

Centralize these config options to a single scan, and store
all of the values in a repo_settings struct. The values for
each setting are initialized as negative to indicate "unset".

This centralization will be particularly important in a later
change to introduce "meta" config settings that change the
defaults for these config settings.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-08-13 13:33:54 -07:00